An immunochromatography (hereinafter, it may be referred to as immunochromato-method) is a diagnostic method using nanoparticles. Being simple to operate and requiring relatively short time of approximately 10 to 30 minutes and no expensive devices for determination, it is widely used as an excellent simple diagnostic method in actual clinical areas. For example, for determination of influenza virus infection, by having a pharynx cotton swab or nasal cavity cotton swab collected from a patient as an analyte, the determination can be made on site within a short time, and thus it is used as a very dominant tool for quick determination of infection.
Colored particles such as gold colloid or colored latex particles are generally used as labeling particles for immunochromatography. However, immunochromatography using colored particles has poor sensitivity, and thus it cannot be used for a test subject containing insufficient amount of a test substance in an analyte. Further, for determination of influenza virus detection, initial stage of infection having no sufficient amount of viruses in an analyte may be found to be negative by immunochromatography using colored particles. For solving these problems, it has been tried to achieve highly sensitive immunochromatography.
As a method of achieving highly sensitive immunochromatography, there is “fluorescence immunochromatography” which uses fluorescent particles as labeling particles (see, WO 2008/018566 A, WO 2007/097377 A and JP-A-2010-197248 A). According to fluorescence immunochromatography, fluorescent lines are detected by using latex particles, silica particles, or semi-conductor nanoparticles having fluorescent characteristics as labeling particles, and therefore highly sensitive determination can be made compared to a naked eye determination of immunochromatography which uses colored particles.